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Posted on Aug 20, 2015

Announcing the D-Wave 2X Quantum Computer

We are very excited to announce the general availability of the latest generation of D-Wave quantum computers, the D-Wave 2X™ system. With 1000+ qubits and many other technological advancements, the D-Wave 2X will enable customers to run much larger, more complex problems on the system.

In addition to scaling beyond 1000 qubits, the new system incorporates other major technological and scientific advancements. These include an operating temperature below 15 millikelvin, near absolute zero and 180 times colder than interstellar space. With over 128,000 Josephson tunneljunctions, the new processors are believed to be the most complex superconductor integrated circuits ever successfully used in production systems. Increased control circuitry precision and a 50% reduction in noise also contribute to faster performance and enhanced reliability.

To characterize performance of the new system we performed a set of benchmark tests against the best known, highly tuned software solvers running on classical systems. The benchmark includes a set of synthetic discrete combinatorial optimization problems intended to be representative of real world challenges.

One of the challenges in benchmarking a quantum processor at the 1000+ qubit scale is that computation time for both quantum and classical processors grows exponentially with problem size. This makes finding the optimal solution to a problem computationally prohibitive at the 1000+ qubit scale of the D-Wave 2X.

Instead of solving for optimal solutions many important optimization applications work to attain near-optimal solutions. Typically, large-scale solvers try to find a solution that is considered ‘close enough’ or they are given a fixed time budget and return the best solution achieved in the specified time.

Following this approach, we established the Time to Target (TTT) metric and compared the performance of the D-Wave 2X on a host of native hardware problems against highly optimized and tuned solvers.

For the D-Wave 2X we measured both computation time (the time to execute the native quantum annealing algorithm) as well as total time, which includes the I/O overhead of inputting the problem and reading out the results. Computation time better reflects the fundamental performance of the quantum processor, as I/O times are technological issues that will continue to be reduced in future generations.

A summary of the TTT benchmark is as follows:

The D-Wave 2X finds near-optimal solutions up to 600x faster (depending on inputs) than comparable times for the best known and highly tuned, classical solvers. This comparison uses the quantum anneal time of the D-Wave processor.

The D-Wave 2X finds near-optimal solutions up to 15x faster than the solvers using total time measurements.

The greatest performance advantage for the D-Wave 2X compared to the software solvers is seen on inputs with more challenging structures than simple random cases that have been the predominant focus in previous benchmarks. This means the hardware performance is showing its best performance against software solvers on hard problem instances.

In cases where it could be calculated, the difference between “near-optimal” and “optimal” is quite small, less than one percent of the latter. The D-Wave 2X is up to 100x faster at finding good near-optimal solutions than optimal solutions.